How to Choose Interior Paint? VOC Content and Mold-Resistant Rating Are the Parameters That Truly Affect Health

Feeling a burning sensation in your nose after moving into a newly renovated home, or your child coughing frequently — a significant part of the cause may be the paint. This article helps you understand the key parameters of interior wall paint.

---

VOC: Volatile Organic Compounds Are the Primary Health Risk

VOC (Volatile Organic Compounds): Organic chemical substances released into the air by paint during application and drying, including benzene, toluene, xylene, ethylbenzene, and others.

Long-term exposure to high-concentration VOC environments may cause headaches, nausea, and respiratory irritation; some components are considered potential carcinogens.

National standard (GB 18582-2020): Interior wall paint VOC content ≤ 80 g/L.

Practical purchase comparison:

Level	VOC Content	Notes
Meets national standard	≤ 80 g/L	Basic threshold
Low VOC	≤ 50 g/L	Better choice
Very low VOC	≤ 10 g/L	Premium product
Zero VOC	≤ 5 g/L (not detected)	First choice for children's rooms and expectant mothers

Consumer council testing data shows that approximately 65% of mainstream brand products currently on the market have undetectable VOC (below the detection limit of 2 g/L); prioritize products with clear labeling when purchasing.

---

Formaldehyde: Requires Separate Attention in Paint

Besides VOC, formaldehyde is also an important testing item. The standard specifies interior wall paint formaldehyde content ≤ 100 mg/kg (GB 18582-2020).

Note: Formaldehyde content in paint meeting the standard does not mean the entire renovation environment has acceptable formaldehyde levels — flooring, adhesives, and wood panels are the primary sources of formaldehyde; paint contributes relatively less, but you should still choose low-formaldehyde products.

---

Mold-Resistant Rating: Essential for Kitchens, Bathrooms, and Humid Regions

Mold-resistant rating (reference JG/T 176 standard):

• Grade 0: No growth (highest grade; no growth in 10-strain test)
• Grade 1: Growth rate < 10%
• Grade 2: Growth rate 10–30%

Applicable scenarios:

• Ordinary bedrooms, living rooms: Grade 1 or above is sufficient
• Kitchens, bathrooms, basements, humid southern regions: Grade 0; no compromise
• Family members with mold allergy history: Use Grade 0 throughout the entire home

---

Contrast Ratio (Hiding Power): The Key to Paint Efficiency

Contrast ratio: The ability of white or colored paint to cover the underlying color when applied to a substrate. Higher contrast ratio means stronger hiding power, and fewer coats needed per area.

The national standard requires interior wall paint contrast ratio ≥ 0.90 (90% hiding). Quality products have contrast ratios > 0.95, achieving complete coverage with just two coats; inferior products may still show the base color even after three or four coats.

---

Scrub Resistance: Determines Paint Durability

High-use areas like kitchens and hallways have walls that are frequently bumped, scuffed, and wiped; scrub resistance determines how long the paint will look good.

Level	Scrub Resistance Cycles	Application
Basic	≥ 300 cycles	National standard minimum requirement
Standard	2,000–5,000 cycles	Mainstream for residential use
High scrub resistance	> 10,000 cycles	Kitchens, hallways, children's rooms

For families with young children, children's rooms should use high scrub-resistant paint for easy regular cleaning of drawings and marks.

---

Construction Considerations

• Primer: Proper construction should include one coat of primer (seals the substrate, improves topcoat adhesion); skipping primer causes topcoat to peel and flake
• Construction temperature: Temperature ≥ 5°C, air humidity ≤ 85%; avoid construction on rainy days
• Ventilation: Ensure thorough ventilation for 72 hours after construction to accelerate VOC emission; recommend ventilating for 2–4 weeks before moving in

---

Parameters in this article are sourced from GB 18582-2020 "Limit of Harmful Substances in Architectural Wall Coatings" and the Guangdong Provincial Consumer Council paint comparative testing public report.